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Need some help regarding color detection and it's position

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I want to detect the color and it's position in an image. I don't get the output. I would be really happy if you could guide me.
Example: Take a red box in a white background at some position. I want to detect the red color and it's position (i.e. co-ordinates) in the image.
Thanks in advance.

Accepted Answer

Chandra Kurniawan
Chandra Kurniawan on 14 Jan 2012
Hi, i Venky
from my previous post, I've improved the code.
This picture below is test image :
Here the code :
Irgb = imread('multiplecolors.jpg');
Ihsv = rgb2hsv(Irgb);
low = 0;
high = 0.04;
h = (Ihsv(:,:,1) >= low) & (Ihsv(:,:,1) <= high);
s = (Ihsv(:,:,2) >= 0.9) & (Ihsv(:,:,2) <= 1);
v = (Ihsv(:,:,3) >= 0) & (Ihsv(:,:,3) <= 1);
mask = uint8(h & s & v);
mask = imclose(mask, strel('disk', 5));
mR = mask .* Irgb(:,:,1);
mG = mask .* Irgb(:,:,2);
mB = mask .* Irgb(:,:,3);
Icolor = cat(3, mR, mG, mB);
Igray = rgb2gray(Icolor);
Ibw = im2bw(Igray,graythresh(Igray));
Ilabel = bwlabel(Ibw);
stat = regionprops(Ilabel,'boundingbox','centroid');
imshow(Irgb); hold on;
for x = 1 : length(stat)
bb = stat(x).BoundingBox;
xc = stat(x).Centroid(1);
yc = stat(x).Centroid(2);
txt = sprintf('x : %.2f\ny : %.2f',xc,yc);
rectangle('position',bb,'edgecolor','b','linewidth',2);
plot(xc,yc,'bo');
text(xc,yc+30,txt,'color','y','fontweight','normal');
end
And the result shown below :
The pink colored object is not detected anymore.
It is so simple like I said. Just adjusting the values of hue, saturation, intensity.
  9 Comments
jyothi
jyothi on 14 May 2014
hey thank u very much then what are the values for other different colors
Image Analyst
Image Analyst on 14 May 2014
Extract them, then enter in a location and find out:
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);

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More Answers (1)

Walter Roberson
Walter Roberson on 13 Jan 2012
You have already been guided in your previous copy of this question.
In order to be guided further, you need to answer the question there as to how exactly you define each color.

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